DOCSLIB.ORG

A Signal-To-Noise Ratio Analysis of an Autoradiographic Image Enhancement Process

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Signal-To-Noise Ratio Analysis of an Autoradiographic Image Enhancement Process Rochester Institute of Technology RIT Scholar Works Theses 8-1-1984 A signal-to-noise ratio analysis of an autoradiographic image enhancement process Donald R. Williams Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Williams, Donald R., "A signal-to-noise ratio analysis of an autoradiographic image enhancement process" (1984). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. A SIGNAL-TO-NOISE RATIO ANALYSIS OF AN AUTORADIOGRAPHIC IMAGE ENHANCEMENT PROCESS by Donald R. Williams A.A .S. ROCHESTER INSTITUTE OF TECHNOLOGY (1978) A thesis submitted in partial fulfillment of the requirements for the degree of Master of SCfence in the School of Photographic Arts and Sciences in the College of Graphic Arts and Photography of the Rochester Institute of Technology August , 1984 Donald R. Williams Signature of the Author _ . Photographic Science and Instrumentation Division Ronald Francis Accepted by . Coordinator, M.S . Degree Program I College of Graphic Arts and Photography Rochester Institute of Technology Rochester, New York CERTIfICATE Of APPROVAL M.S. DEGREE THESIS The M.S. Degree Thesis of Donald R. Williams has been examined and approved by the thesis committee as satisfactory for the thesis requirement for the Master of Science degree Edward M. Grahger Dr . Edward M. Grahger. Thesis Advisor John Carson Mr. John Carson James Jakubowski Mr. James Jakubowski Date ;i A SIGNAL-TO-NOISE RATIO ANALYSIS OF AN AUTORADIOGRAPHIC IMAGE ENHANCEMENT PROCESS by Donald R. Williams Submitted to the Photographic Science and Instrumentation Division in partial fulfillment of the requirements for the Master of Science degree at the Rochester Institute of Technology ABSTRACT A signal-to-noise ratio(SNR) analysis of a S-35 thiourea autoradiographic image enhancement process incorporating subproportional bleaches is performed, with emphasis on diagnostic medical Imagery. Quantifying SNR through a spatial frequency definition of DQE and NEQ, these metrics were compared between donor and receiver-composite stages. While improvements in radiometric speed and gamma were noted in the receiver-composite, these gains were more thanXffset in a SNR sense by correspondingly lower MTF and higher Wiener spectrum values. As a result the donor's DQF^^ of .30 exceeded that of the receiver-composite's by 50%. DQEmavImCXA Similarly, exceeded that of the receiver composite's 350%. the donor's NEQ av by max . The donor's DQE and NEQ continued to exceed that of the receiver-composite even on an equi -exposure basis. TV ACKNOWLEDGEMENTS The author wishes to thank the following for both technical and facility support in the completion of this thesis: Dr. E.M. Granger, Mr. John Carson, 4 Mr. James Jakubowski for both technical support, and in their capacity as thesis committee members. Mr. Phillip Bundh and his colleagues at the Kodak Research Laboratories, Rochester,N.Y.. Xerox Corp., Webster, N.Y., for microdensitometer and computer facility access. Dr. Plewes and Dr- Owunwanne of Strong Memorial Hospital, University of Rochester, Rochester, N.Y. and Mr. Roland Porth for use of the MTF computer programs. TABLE OF CONTENTS Page INTRODUCTION 1 1 . 1 Autoradi ography 2 1.2 Signal Detection and Signal to Noise Ratio 4 1.3 Statement of the Problem 13 EXPERIMENTAL 16 2.1 Image System Definition 17 2 . 2 Samp! e Generati on 22 2.2.1 Donor and Receiver Photographic Materials 24 2.2.2 Donor Screen/Film Exposure and Sensitometry 24 2.2.3 Chemical Processing 25 2.2.4 Receiver Film Exposure 26 2.3 Data Capture and Processing 26 2.3.1 Densitometry- macro 4 micro 27 2.3.2 Characteristic Curve Data Acquisition 28 2.3.3 Characteristic Curve Data Processing 28 2.3.4 MTF Data Acquisition 29 2.3.5 MTF Data Processing 30 2.3.6 Wiener Spectra Data Acquisition 32 2.3.7 Wiener Spectra Data Processing 32 RESULTS 35 3 . 1 Characteristic Curves 36 3.2 Modulation Transfer Function 38 3.3 Wi ener Spectra 39 3.4 DQE and NEQ 41 3.5 DQE and NEQ Error Analysis 42 DISCUSSION 55 56 4 . 1 Characteristic Curves 4.2 Modulation Transfer Function 59 4.3 Wiener Spectra 61 4.4 DQE and NEQ 67 4.5 Applications of DQE and NEQ 72 CONCLUSIONS 77 vi 6. REFERENCES 87 7. APPENDICES 89 7.1 Appendix A - Equipment, Processing, 4 Measurement Parameters 90 7.2 Appendix B - Calculations 4 Curve Fits 96 7.3 Appendix C - Supplemental Graphs 106 7.4 Appendix D - Computer Programs 128 8. VITA 139 vn LIST OF FIGURES Figure # Page 1 X-Ray exposure scenario 18 2 Image chain block diagram 21 3 Experimental procedure block diagram 23 4 Characteristic curves for donor 4 receiver-comp 45 5 Gamma vs. log exposure curves 46 6 MTFs for donor and receiver-comp 47 7 Wiener spectra for donor 4 receiver-comp @ 0=1.0 48 8 Wiener spectrum for donor vs. log exp. 4 frequency 49 9 Wiener spectrum for rec.-comp. vs. log exp. 4 frequency 50 10 Equi -frequency Wiener spectrum values vs. log exposure 51 11 Equi -frequency Wiener spectra with characteristic curves 52 12 Donor DQE and NEQ vs. log exposure 53 13 Receiver-comp. DQE and NEQ vs. log exposure 54 14 Receiver-comp: donor gamma ratio vs. log exposure 58 15 MTF comparisons to reference 38 60 16 Rossman's Wiener spectrum model 62 2 17 MTF 4 Wiener spectra comparisons 64 18 Wiener spectra @ .4 vs. density 65 19 Receiver-comp. : donor DQE ratio vs. log exposure 69 20 Donor DQE and receiver-comp. NEQ comparison vs. log exp 74 21 Image chain block diagram 81 22 Characteristic curves for donor 4 receiver-comp 82 23 MTFs for donor and receiver-comp 83 24 MTF comparisons to reference 38 83 spectra with 25 Equi -frequency Wiener characteristic curves 84 26 Donor DQE and NEQ vs. log exposure 85 27 Receiver-comp. DQE and NEQ vs log exposure 86 vm 1. INTRODUCTION 1.1 Autoradiography As photography evolved from an art to a science, a natural consequence was the evaluation and extension of the photographic image as an information medium. This spawned a plethora of techniques to enhance the photographic image Information beyond what was considered to be normal. Even to this day new techniques continue to be proposed. However, only a handful of these methods survived the gauntlet of practicality and success. One of these processes which, at first, did not appear especially appealing from an image enhancement perspective was a 1 * 2 radiation emission method . Over the years this method has come to be known as autoradiography. Basically, the procedure involves toning the original silver 1mage(the donor) with a radioactive material. When the toned image was placed 1n contact with another unexposed silver halide material (the receiver), the decay properties of the radioactive material led to a subsequent latent image in the receiver. Since the amount of toner and with it radiation emissiond.e., exposure) is proportional to the amount of silver at a given location, wherever there was a high density in the donor there was a proportional amount of latent image or, after development, density. Likewise, low donor densities led to low receiver densities. Therefore, upon development, the receiver was a duplicate positive Image of the donor. While this method was originally intended as a duplication scheme, It eventually found a use as an image 3 enhancement method . The Idea behind the enhancement 1s to radioactively tag the donor's image silver that does not contribute significantly to the optical density yet does contain image information. Most of this information 1s In the toe region of the characteristic curve and is associated with individual Image grains rather than a large number of grains. By radioactively tagging this silver one hopes that the information in this region will manifest itself 1n the receiver, and in turn increase the photographic speed. The feasability of recent efforts using this scheme has suffered however due to inherent radiation hazards, equipment considerations and unacceptable image quality.4. Be that as it may, one process that has shown considerable promise and seems to circumvent some of the above mentioned problems is an autoradiographic image Intensification method developed by Askins . Similar to the radiation emission method, the original silver image of the donor 1s reacted with Askins' radioactive nuclides. For s process these are beta-particle emitting nuclides and because of their low energy tend to optimize the enhanced image's resolution. These nuclides take the form of thiourea S-35 in an activating or toner bath. Once the donor has been bathed in this activating bath It 1s dried, and one then has a radioactive Image whose radioactive flux at any location is proportional to the amount of silver at that point. This radiotoned film is then placed 1n contact for a given duration of time with another silver halide emulsion, the receiver, and subsequently developed as one would a normal Image from silver halide materials. The chemical mechanism behind the procedure can best be o described through work done by James and Vanselow . It is believed that the silver ion reacts with the thiourea through the thione OH" RCNH2=S presence of ion the yielding Ag+. In the , following reaction occurs: ^C=S*-Ag+ + OH"-*- HN = C-S-Ag + HgO (1). H2N However, at higher pH the silver thiourea compound reacts via the equation: f ? Ag+? OH" = + = HN C-S-Ag + -#- Ag,S + RC N + H,0 (2), With respect to Askin's process, any silver existing in the donor material 1s aerially oxidized to Ag+.
Load more

Recommended publications
  • Basic Sensitometry and Characteristics of Film Basic Sensitometry and Characteristics of Film
    BASIC SENSITOMETRY AND CHARACTERISTICS OF FILM BASIC SENSITOMETRY AND CHARACTERISTICS OF FILM BASIC PHOTOGRAPHIC SENSITOMETRY Sensitometry is the science behind the art of filmmaking. It is the measurement of a film’s characteristics. These measurements are expressed in numeric and chart form to convey how a film will react to the amount of light, the type of lighting, the amount of exposure, the type of developer, the amount of development, and how all these factors interact. In most cases, a cinematographer doesn’t need a great depth of technical information to use motion picture films—using the right film speed and the right process will suKce. On the other hand, having a basic understanding of film sensitometry will help you in tasks as simple as film selection to as complicated as communicating the mood of a challenging scene. THE CHARACTERISTIC CURVE At the heart of sensitometry is the characteristic curve. The characteristic curve plots the amount of exposure against the density achieved by that exposure: 3.0 2.8 2.6 2.4 Shoulder 2.2 2.0 1.8 Y Straight Line T 1.6 I S 1.4 N E D 1.2 1.0 Base-Plus-Fog or 0.8 Gross-Fog Density 0.6 Toe 0.4 0.2 0.0 3.0 2.0 1.0 0.0 1.0 2.0 LOG EXPOSURE To create a characteristic curve, we first need some densities to plot, and they come from a sensitometric tablet exposed onto the film. Commonly called a step tablet, this highly calibrated tool consists of 21 equally spaced intervals of grey.
    [Show full text]
  • Redacted for Privacy E
    AN ABSTRACT OF THE THESIS OF RICHARD EUGENE GROSS for the MASTER OF SCIENCE (Name) (Degree) General Science in(Radiological Physics) presented on ,20j /9. (Major) (Date) Title: A STUDY OF RELATIVE SPEEDS OF MEDICAL X-RAY FILM AND INTENSIFYING SCREEN COMBIN4TIONS Abstract approved: Redacted for Privacy E. Dale Trout The objective of this study was to determine the relative speeds of available medical x-ray films exposed directly to x-rays and expo- sed in combination with various types of intensifying screens.The information obtained from this sensitometric data was used to obtain factors by which a radiographic exposure technique with one film- screen combination could be modified to obtain an adequate radio- graph with any of the other films or film-screen combinations. All of the films were exposed using a conventional diagnostic x-ray machine and processed in an automatic processor.The sen- sitometric data were tested by producing radiographs with the various films and film-screen combinations using the basic exposure techni- que and the exposure factors obtained from the relative speeds.The radiographic subject was a phantom made of tissue equivalent plastic which encased human skeletal parts.The radiographic results of the testing indicated that adequate radiographs can be obtained using this data. Assuming that the basic radiograph has an average density of 1.0, a second radiograph using a different film-screen combination will have an average density which will not deviate from 1.0 by more than f 0. 15. A Study of Relative Speeds
    [Show full text]
  • Sample Manuscript Showing Specifications and Style
    F. Cao, F. Guichard, H. Hornung, R. Teissières, An objective protocol for comparing the noise performance of silver halide film and digital sensor, Digital Photography VIII, Electronic Imaging 2012. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. http://dx.doi.org/10.1117/12.910113 An objective protocol for comparing the noise performance of silver halide film and digital sensor Frédéric Cao, Frédéric Guichard, Hervé Hornung, Régis Tessière DxO Labs, 3 Rue Nationale, 92100 Boulogne, France ABSTRACT Digital sensors have obviously invaded the photography mass market. However, some photographers with very high expectancy still use silver halide film. Are they only nostalgic reluctant to technology or is there more than meets the eye? The answer is not so easy if we remark that, at the end of the golden age, films were actually scanned before development. Nowadays film users have adopted digital technology and scan their film to take advantage from digital processing afterwards. Therefore, it is legitimate to evaluate silver halide film “with a digital eye”, with the assumption that processing can be applied as for a digital camera. The article will describe in details the operations we need to consider the film as a RAW digital sensor. In particular, we have to account for the film characteristic curve, the autocorrelation of the noise (related to film grain) and the sampling of the digital sensor (related to Bayer filter array).
    [Show full text]
  • The Essential Reference Guide for Filmmakers
    THE ESSENTIAL REFERENCE GUIDE FOR FILMMAKERS IDEAS AND TECHNOLOGY IDEAS AND TECHNOLOGY AN INTRODUCTION TO THE ESSENTIAL REFERENCE GUIDE FOR FILMMAKERS Good films—those that e1ectively communicate the desired message—are the result of an almost magical blend of ideas and technological ingredients. And with an understanding of the tools and techniques available to the filmmaker, you can truly realize your vision. The “idea” ingredient is well documented, for beginner and professional alike. Books covering virtually all aspects of the aesthetics and mechanics of filmmaking abound—how to choose an appropriate film style, the importance of sound, how to write an e1ective film script, the basic elements of visual continuity, etc. Although equally important, becoming fluent with the technological aspects of filmmaking can be intimidating. With that in mind, we have produced this book, The Essential Reference Guide for Filmmakers. In it you will find technical information—about light meters, cameras, light, film selection, postproduction, and workflows—in an easy-to-read- and-apply format. Ours is a business that’s more than 100 years old, and from the beginning, Kodak has recognized that cinema is a form of artistic expression. Today’s cinematographers have at their disposal a variety of tools to assist them in manipulating and fine-tuning their images. And with all the changes taking place in film, digital, and hybrid technologies, you are involved with the entertainment industry at one of its most dynamic times. As you enter the exciting world of cinematography, remember that Kodak is an absolute treasure trove of information, and we are here to assist you in your journey.
    [Show full text]
  • An Exposure Indicator for Digital Radiography Report of AAPM Task
    AAPM REPORT NO. 116 An Exposure Indicator for Digital Radiography Report of AAPM Task Group 116 July 2009 DISCLAIMER: This publication is based on sources and information believed to be reliable, but the AAPM and the editors disclaim any warranty or liability based on or relating to the contents of this publication. The AAPM does not endorse any products, manufacturers, or suppliers. Nothing in this publication should be interpreted as implying such endorsement. © 2009 by American Association of Physicists in Medicine DISCLAIMER: This publication is based on sources and information believed to be reliable, but the AAPM, the editors, and the publisher disclaim any warranty or liability based on or relating to the contents of this publication. The AAPM does not endorse any products, manufacturers, or suppliers. Nothing in this publication should be interpreted as implying such endorsement. ISBN: 978-1-888340-86-0 ISSN: 0271-7344 © 2009 by American Association of Physicists in Medicine All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of the publisher. Published by American Association of Physicists in Medicine One Physics Ellipse College Park, MD 20740-3846 AAPM REPORT NO. 116 An Exposure Indicator for Digital Radiography Report of AAPM Task Group 116 Co-Chairs S. Jeff Shepard Jihong Wang Imaging Physics Department #056 Division of Diagnostic Imaging The University of Texas M.D. Anderson Cancer Center Houston, TX 77030 Task Group Members: Michael Flynn, Henry Ford Hospital, Detroit, MI Eric Gingold, Thomas Jefferson University, Philadelphia, PA Lee Goldman, Hartford Hospital, Hartford, CT Kerry Krugh, Toledo Hospital, Toledo OH David L.
    [Show full text]
  • Sensitometry in Canadian Aerial Survey
    P. D. CARMAN National Research Council of Canada Ottawa, Ontario KIA OR6, Canada Sensitometry in Canadian Aerial survey The NRC Sensitometer, its design goals, its design features and reasons for their choice, some evolutionary changes, methods of calibration and verification, and some of the sensitometric studies it has facilitated, are described. photography was done by the Royal Canadian Air Force. They encountered occasional problems in ENSITOMETRIC CONTROL of aerial photography is diagnosing negative faults. For example, thin S needed for consistent optimized quality. A negatives might be variously blamed on under ex- sensitometric exposure on every roll of film pro- posure, under development, or defective film, vides a continuing check of film and processing, with no clear evidence for a choice. This problem accumulates a useful background of information, was submitted to the Joint RCAF-NRC Photo- and aids early detection and correction of any graphic Research Committee, which recom- problems. Advance knowledge of the speeds and mended printing a calibrated sensitometric expo- gradients of the actual films available, under vari- sure on every roll of film. Sensitometers for this ous conditions of development, permits optimum use were calibrated in absolute terms by the Na- selection of film, development, lens aperture, tional Research Council's Optics Laboratory so ABSTRACT:The advantages of sensitometric control of the processing of aerial films became apparent and was brought into common use in Canada about 1943, first by the Royal Canadian Air Force and later by private companies. A sensitometer specifically for this purpose was designed at the National Research Council in 1956-57.
    [Show full text]
  • The Soft-Focus Lens and Anglo-American Pictorialism
    THE SOFT-FOCUS LENS AND ANGLO-AMERICAN PICTORIALISM William Russell Young, III A Thesis Submitted for the Degree of PhD at the University of St. Andrews 2008 Full metadata for this item is available in the St Andrews Digital Research Repository at: https://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/505 This item is protected by original copyright This item is licensed under a Creative Commons License The Soft-Focus Lens and Anglo-American Pictorialism William Russell Young, III B.S.B.A., M.B.A., M.A. Submitted in fulfillment of the requirements for Doctor of Philosophy April 30, 2007 Declarations (i) I, William Russell Young, III, hereby certify that this thesis, which is approximately 90,000 words in length, has been written by me, that it is the record of work carried out by me and that it has been written by me and that it has not been submitted in any previous application for a higher degree. April 30, 2007 ______________________________ William Russell Young, III (ii) I was admitted as a research student in January, 2001, and as a candidate for the degree of Doctor of Philosophy in Art History; the higher study for which this is a record was carried out in the University of St. Andrews between 2001 and 2007. April 30, 2007 _______________________________ William Russell Young, III (iii) I hereby certify that the candidate has fulfilled the conditions of the Resolution and Regulations appropriate for the degree of Doctor of Philosophy in the University of St.
    [Show full text]
  • Glossary of Motion-Picture Terms Glossary of Motion-Picture Terms
    GLOSSARY OF MOTION-PICTURE TERMS GLOSSARY OF MOTION-PICTURE TERMS — # — 1D LUT: A 1-dimensional lookup table is a static color translation table that converts one input value to one output value. There is a 1-to-1 correspondence in the input and output values in a 1D LUT. 16 mm: The frame is one-fourth the size of a 35 mm frame and has a 1.33:1 television aspect ratio. The film can have perforations on both sides or on just one side. When compared to 35 mm, grain is more apparent. 2K: A digital image 2048 pixels wide. A standard 2K scan of a full 35 mm film frame is 2048 X 1556 pixels. 3:2 Pull-down: The telecine transfer relationship of film frames to video fields. Film shot at 24 fps is transferred to 30 fps NTSC video with an alternating three-field/two-field relationship. 3D LUT: A 3-dimensional lookup table is a static color translation table that converts a set of three input color values to another set of three output color values. 35 mm: The standard gauge for professional filmmakers, and the standard mainstream film format used for theatrical releases. 4K: A digital image 4096 pixels wide. A standard 4K scan of a full 35 mm film frame is 4096 X 3112 pixels. 65 mm: The camera film format (size) for wide-screen formats such as IMAX. 70 mm: The release print format (size) for wide-screen formats such as IMAX. — A — A Wind: When you hold a roll of 16 mm or other single-perf film so that the film leaves the roll from the top and toward the right, the perforations will be along the edge toward the observer.
    [Show full text]
  • Silver Halide and Silicon As Consumer Imagers
    2000 International Symposium on Silver2000 Halide International Technology Symposium on Silver Halide Technology Copyright 2000, IS&T Silver Halide and Silicon as Consumer Imagers Richard P. Szajewski Eastman Kodak Company Rochester, New York, USA 14650 Abstract camera film and the mean exposure at a focal plane in an automatic camera, ISO-2721, is: An appreciation of the potential of silver halide as an image capture material for digital applications can benefit from an ISO = 10 lux-seconds/H (1) understanding of the characteristics and potential of silicon- where: ISO is the speed rating, a dimensionless number; and based imagers. Here, we compare the imaging H, in lux-seconds, is the minimum mean focal plane characteristics of contemporary silicon and AgX imagers on exposure required to produce the first excellent image. The a common basis. Sensitometric and image structure scaling constant for films with well-defined latitude is comparisons of first generation Kodak Advantix 400 AgX typically about 10. Distinct scaling constants and reference color film and contemporary (1997–1998) Kodak exposure points are employed for films with less well Professional digital camera system (DCS) color imagers at defined latitudes. Consideration of typical scene luminance 393K, 1.6M, and 6.3M sensor resolution are presented. The ranges and allowance for exposure errors leads to a imagers compared have similar useful color imaging minimum useful latitude of about 2.5 log E, centered about exposure thresholds. In speed-grain terms, the 6.3M sensor the camera normal exposure H. DCS, which retails at more than $25,000, provides similar speed-grain in the lower scale and superior speed-grain in the upper scale when compared to the AgX film.
    [Show full text]
  • General Disclaimer One Or More of the Following
    https://ntrs.nasa.gov/search.jsp?R=19710023339 2020-03-11T22:14:59+00:00Z View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NASA Technical Reports Server General Disclaimer One or more of the Following Statements may affect this Document This document has been reproduced from the best copy furnished by the organizational source. It is being released in the interest of making available as much information as possible. This document may contain data, which exceeds the sheet parameters. It was furnished in this condition by the organizational source and is the best copy available. This document may contain tone-on-tone or color graphs, charts and/or pictures, which have been reproduced in black and white. This document is paginated as submitted by the original source. Portions of this document are not fully legible due to the historical nature of some of the material. However, it is the best reproduction available from the original submission. Produced by the NASA Center for Aerospace Information (CASI) N71 3 81 5 0^ (ACCESSION''' UMBER) _0 — cc (CODr-) } tA-) 1 -z <u CR OR TMX : - AD NUMBER) (CA iE OP.Y) 1p H REMOTE SENSING APPLICATIONS IN FORESTRY 1 C J p CALIBRATION OIL COLOR AERIAL PH _)"S"Vt°)GRAPHY by Robert W. liana Pacific Southwest Forest and Range Experiment Station Forest Service, U. S. Department of Agriculture Special Report 30 June 1971 A report of research performeel under the auspices of the I . Forestry Remote Sensing Laboratory, School of Forestry and Conservation University of California Berkeley, California A Coordination Task Carried Out in Cooperation with The Forest Service, U.S.
    [Show full text]
  • The Effect of Environment on Latent Image Formation and Stability
    IS&T's 1999 PICS Conference The Effect of Environment on Latent Image Formation and Stability Sean W. P. O’Toole Eastman Kodak Company Rochester New York Richard K. Hailstone Rochester Institute of Technology Rochester, New York Abstract als using an exposure time that causes minimal LIRF. The effects of oxygen and water vapor were determined This paper uses an unsensitized emulsion and two by observing latent-image stability and initial photo- chemically sensitized emulsions to investigate the effect graphic speed in several environments. An unsensitized of oxygen and water vapor on latent image formation and and two chemically sensitized emulsions were used to stability. Storage of a latent image in a humidified envi- observe the effect of chemical sensitization on latent- ronment will induce a speed loss in some emulsions. The image formation and stability. unsensitized emulsion was the most sensitive to envi- ronment while the sulfur-plus-gold-sensitized emulsion II. Previous Investigations was not. This is presumably due to the composition and size of the latent image. Maximum changes over time The following paragraphs outline several selected inves- require the presence of both oxygen and water vapor. Ex- tigations relevant to this thesis. Theory of the Photogra- tended development and gold latensification restored phic Process, edited by T. H. James, is an additional ref- some of the speed loss observed with the unsensitized erence for many of the topics discussed in this section.1 emulsion. The unrecovered speed loss is due to either In 1872, Lt. Col. Wortley2 wrote to the British Journal latent-image centers being completely oxidized or being of Photography concerning photographic sensitivity.
    [Show full text]
  • Satellite Digital Photography: Preserving the Image in the Digital-To-Analog Conversion
    IS&T’s 1999 PICS Conference IS&T's 1999 PICS Conference Satellite Digital Photography: Preserving the Image in the Digital-to-Analog Conversion Jerome R. Noss Autometric, Incorporated Springfield, Virginia, USA Abstract element (pixel) of the sensor array. The spatial resolution of Landsat Thematic Mapper data is 30 x 30 meters for each of The preparation of full-color photographic hardcopy from six visual and infrared (IR) bands and 120 meters for one digital data acquired by civilian imaging satellites has been a thermal IR band. SPOT delivers 10 meter spatial resolution standard practice since the launch of the first Landsat in 1972.1 from one panchromatic band and 20 meter data from three Satellite digital imaging provides broad area coverage of ter- multispectral bands.2-3 rain features by composites of data from visible and non-vis- Raw imaging data transmitted by the satellite typically ible spectral bands. Analyses and interpretations of the dis- undergoes a series of preprocessing routines to correct for played features are blends of inference, measurement, and geometric and radiometric corrections.4-5 Variations in the po- the assessment of terrestrial change over time. Largely over- sition of the satellite during data acquisition influence the geo- looked in the production of satellite photographs is the sig- metric accuracy of the image structure. Algorithms based on nificant loss of original imaging data that occurs in its con- tracking data from the ground station are written to math- version to a photographic end product. This paper presents ematically adjust for such distortions before the image is re- an overview of the digital-to-analog conversion process and leased as a working database.
    [Show full text]